A fibroadenoma is a benign growth of the breast that is made up of fibrous tissue (fibro) and glandular elements (adenoma).
This is the second most common incidental lesion found on breast ultrasound. The most common being a breast cyst.
It has no increased risk of turning into a cancer when compared to the rest of the breast.
A lesion may be called a fibroadenoma on ultrasound but can only be confirmed as a fibroadenoma with a biopsy.
Some lesions may be followed up with serial ultrasounds to confirm their benign nature. This may be done if there are many similar looking lesions which all look benign where the largest may be biopsied. The rest can be followed up with ultrasound only unless they change / enlarge.